Illuminated dial



Oct. 26, 1965 D, E. PRo'rzMANN ILLUMINATED DIAL Filed Sept. l5, 1962 'installation in standard instruments.

United States Patent 3,214,577 ILLUMINATED DIAL Donald E. Protzmann, Athens, Ga., assignor to General Time Corporation, New York, N.Y., a corporation of Delaware Filed'Sept. 13, 1962, Ser. No. 223,416 8 Claims. (Cl. 240-2.1)

VThis invention relates generally to dial assemblies for clocks or other information displaying instruments and concerns more particularly an illuminated dial of this type.

,It is an object of the invention to provide an illuminated dial assembly utilizing a single light source which develops peripheral illumination completely around, and across, the .dial display field.

Another object is to provide a dial assembly of the above type which is quite versatile in that a wide variety of illuminativev and decorative effects can be obtained by slightly modifying the basic structure of the invention.

It is also an object to provide a dial assembly as characterized above which is quite compact and well suited for Moreover, the dial assembly ofthe invention is inexpensive to manufacture and easyl to install so as to be suitable for high volume production.

Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which:

FIGURE l is a transverse section through a Wall clock embodying a dial assembly of the invention;

FIG. 2 is a rear elevation of the dial assembly member appearing in FIG. land is taken approximately along the Iline 2-2 in FIG. l;

FIG. 3 is a bottom view of the member shown in FIG. 2;

FIG. 4 is an enlarged fragmentary view taken approximately along the line 4--4 in FIG. 2;

FIG. 5 is a fragmentary enlarged view similar to FIG. 2 showing ,a modified form of dial assembly member; and

FIG. 6 is a fragmentary section taken approximately along 4the line 6--6 in FIG. 5.

While the invention will be described in connection with certain preferred embodiments, it will be understood that l do not intend to vlimit `the invention to those embodiments. On the contrary, I intend to cover all alternatives, modifications andequivalents as may be included within the spirit and scope of the invention as defined by the appended claims. l

Turning first to FIG. 1, there is shown an information displaying instrument taking the form of a wall clock 10 having an illuminated dial assembly embodying the invention. The clock 10V includes a molded housing 16 which is circular ink general configuration and within which are mounted front and rear timing train frame plates 17 and 18, respectively. A synchronous electric motor 19 is mounted within the housing 16 on the rear frame plate 18 and is coupled through a conventional timing train, not shown, to a shaft and sleeve stack 20 which supports the usual second, minute and hour hands 21, 22 and 23, respectively. The hands 21-23 sweep over the dial assembly 15 and are enclosed within a transparent lens 24.

In accordance with the invention, the dial assembly 15 includes a cup-shaped member of light transmitting material `having a substantially flat display field face 31 from which light is dispersed and which is peripherally lighted byasingle lamp 32. Preferably, the member 3f) isl unitarily formed of; clear polystyrene or of an acrylic resin suchv as Lucite or Plexiglas The member 30 includes a peripheral flange 33 which is curved from the display field face 31 and formed with a notch opening 34 ICC which receives the lamp 32. In the illustrated construction, the lamp 32 is mounted in a socket 35 formed integrally with and within the clock housing 1,6. The lamp 32 is generally alined With the side edges of the notch 34 so that light from the lamp is carried` peripherally ,about the member 30 within the flange 33.

The edge of the flange 33 is stepped at angularly spaced points about the display field face 31 so as to delinenternally reflecting surfaces 37 vthat direct light from the lamp opening 34 toward the curved portion ofthe member 30. In the illustrated embodiments, there are twelve surfaces 37 spaced evenly about the member 30 at 45 angles with respect to lines 38 that are perpendicular to the display field f-ace 31 (see FIG. 4). The surfaces 37 all have approximately the same surface area and, asa result, the light traveling from the lamp 32 aboutthe flange 33 is reflected by the surfaces 37 so as to define twelve rays of approximately equal intensity which are positioned where the hour indicia marks would normally fall on the display field face 31. Each ray is well defined as a result of forming the edges of the surfaces 37 quitev sharply.

It will be noted that the lamp v32 is positioned within the notch 34 a distance that at least equals the depth of the V defining the reflecting surfaces 37 positioned at the directly opposite side of the member 30. In `this way, each of the reflecting surfaces 37 receives approximately the same :amount of light so that each ray has about the same intensity. Because of the 45 angle disposition of the surfaces 37, the light is reflected so that the rays move perpendicularly toward the face 31.

The curved portion between the flange 33 and the display field face 31 has an outer radius 41 (see FIG. 3) that is effective to channel light from the reflecting surfaces 37 into the display field face portion. If the mem-y ber 30 is formed of light-transmitting plastics of the type referred to above, this radius should be atleast three times the thickness of the material so as to insure total internal reflection. This standard rule of thumb for lightconducting plastics is, of course, also applicable to the curve of the flange 33 about the periphery of themernber 30. Since the illustrated member 30 is circular, this minimum curve is not particularly critical in the exemplary embodiment but this factor should be considered in forming rectangular or other dial assemlies having well defined corners.

To disperse the light over the display field face portion of the member 30, this portion is tapered in 4thickness inwardly from the flange 33. In the preferred embodiment, the display field face 31 is planar and the back surface of this portion of the member 30 slopes uniformly toward a central opening 42 which fits over the stack 20. This uniform tapering results in light being retracted forwardly from the display field face 31 with uniform intensity from the flange 33 to the stack 20. Preferably, an annular opaque shield 45 is mounted between the member 30 andv the dial assembly lens 24 so as to expose only the center area of the display field face 31.

One `of the important features of the dial assembly 15 is its versatility and adaptability with respect to producing `different effects. For example, in the FIG. v1 embodiment, a diffuser screen 46 of translucent anaterial is disposed over the face 31 within the lens 24 so that a uniform glow over the entire dial assembly is 'obtained rather than distinct light rays. The numerals `or indicia marks which are desired may be applied directly tothe diffuser 46 or, of course, the diffuser may be eliminated and the hour marks applied directly to the face 31. As a further modification, the edges of the reflecting surfaces 37 may be rounded so that light isy reflected in a fanned-out pattern rather than in distinct aguas?? rays. In addition, the surfaces 37 can be formed with varying areas so as to vary the intensity of the light at different points across the display field face 31.

In FIGS. 5 and v6, a modified cup-shaped dial assembly member 30a is shown which corresponds to the member 30 previously described but which includes a pattern 50 in the rear surface of the display field face portion of the member. In this embodiment, the pattern 50 is formed of a series of concentric circles cut into the material of the member 30a so as to produce a particular decorative effect resulting from the pattern in which the rays of light are refracted by the circles. In addition, the member 30 is formed with indicia marks 51 .formed integrally on the display field face 31a of the member 30a. The marks 51 are disposed at the usual increments s-o as to indicate the hour positions of a clock.

It will be obvious that the pattern 50 could be mottled or etched in any desired configuration for special decorative effects. In addition, the angles at which the reflecting Vsurfaces 37a of the member 30a are disposed can be selected so as to spotlight special decorative features.

It will be readily apparent that the dial assembly 15, utilizing either the member 30 or the modified member 30a, can be quite readily adapted to a clock or similar information displaying instrument sin-ce the cup-shaped configuration of the members 30, 30a adapt readily to a compact arrangement requiring little modification of the instrument or its housing. Moreover, the easily formed and one piece c-onstruction of the members 30 and 30a, together with the fact that only a single light source is utilized, makes the dial assembly of the invention inexpensive to manufacture and easy to install s-o that it is well suited for high volume production.

I claim as my invention:

1. An illuminatable dial comprising a cup-shaped member of light transmitting material having a display field face portion and a peripheral flange, said flange having a lamp receiving opening therein, the edge of said flange being stepped so as to define internally reflecting surfaces inclined transversely of the flange and with respect to said face portion for directing light moving peripherally of said face portion from said opening toward the face portion of said member, and said display field face portion of the member being tapered in thickness inwardly from said flange so as to disperse light from said flange over said face.

v2. An illuminatable dial comprising a cup-shaped member of light transmitting material having a substantially flat display field face portion and an annular peripheral flange curved from said face, said flange having a lamp receiving opening therein, the edge of said flange being stepped at angularly spaced points about said face so as to define internally reflecting surfaces for directing light from said opening toward the curved portion of said member, the outer radius of said curved portion being effective to channel light from said flange to said field face portion, and sai-d display field face portion being tapered in thickness inwardly yfrom said flange so as to disperse light from said flange over said face.

3. An illuminatable dial comprising a cup-shaped member of light transmitting material having a substantially flat display field face portion and a peripheral flange curved from said face, said flange having a lamp receivingnotch therein, the edge of said flange being stepped at angularly spaced points about said face so as to define internally reflecting surfaces for directing light from said notch toward the curved portion of said member, the outer radius of said curved portion being effective to channel light from said flange to said field face portion, and said displayA field 'face portion having a substantially flat face merging with said outer radius and an opposite surface tapered in thickness inwardly from said flange so as to disperse light from said flange over said face.

` 4. An illuminatable dial comprising a cup-shaped mem- 'ber of llight transmitting material having a substantially flat display field face portion and a peripheral flange curved from said face, said flange having a l'a-mp receiving -opening therein, the edge of said lflange being stepped at angularly spaced points about said face so as to define :internally reflecting surfaces for directing light from said opening toward the curved p-ort-ion of said member, the outer radius of said curved portion being effective to channel light from said flange to said field face portion, and .said display field face portion having a design pattern formed therein and being tapered in thickness inwardly from said flange so as to disperse light from said flange =over said face in accordance with said pattern,

5. An illuminatable dial comprising a 'cup-shaped member of light transmitting material having a substantially flat display field face portion and an annular peripheral flange curved from said face, said flange having a lamp receiving opening therein, the edge -of said flange being stepped at angularly spaced points about said face so as to define internally reflecting surfaces inclined transversely of the flange and with .respect to said face portion for directing light movin-g peripherally of said face portion from said opening toward the curved portion of said mem- Iber, the outer radius of said curved portion being effective to channel light from said flange to said field face portion, said display field face portion having an angularly spaced pattern of deformations formed therein, and said reflecting surfaces being disposed to direct a discreet ray of light to each of said deformations.

6. In an instrument dial assembly, the combination -comprising a housing, a cup-shaped member of light transmitting material having a display field face portionmounted in said housing, said member also having a peripheral flange, a lamp mounted in said housing so as to extend int-o an opening formed in said flange, the edge of said flange being stepped so as to define internally reflecting surfaces inclined transversely of the flange and with respect to said face portion for directing light moving peripherally of said face portion from said lamp toward the face portion lof said member, and said display field face portion being tapered in thickness inwardly Afrom said fflange so as to disperse light from said lamp over said l ace.

7. yIn an instrument dial assembly, the combination comprising a housing, a cup-shaped member of light transmitting material having a substantially at display field face portion mounted in -said housing, said member also having a peripheral flange curved from said face port-ion at a radius effective to channel light from said flange to within said field face portion, a lamp mounted in said housing so as to Iextend into an opening formed in said flange, the edge of said flange being stepped at angularly spaced points about said face so as to define internally refleeting surfaces for directing light from said lamp toward the curved portion of said member, said display field face portion being tapered in thickness inwardly `from said flange s-o as to disperse light from .said lamp over said face, Iand a shield mounted in said housing over said member so .as to externally expose only said display field face portion.

8. `In an instrument dial assembly, the combination comprising a housing, a cup-shaped member of lighty transmitting material having a substantially flat display field face portion mounted in said housing, said member also having a peripheral flange curved from said face portion at a radius effective to channel light from said flange to within said field face portion, a lamp mounted in said housing so as to extend into an opening formedk display eld face portion, .and a translucent diuser `disposed over said externally exposed area of the display eld face portion.

References Cited bythe Examiner UNITED STATES PATENTS Bassett 240-1 Hudson 240-1 Anderson et a1. 240--1 Albnger 240-1 NORTON ANSHER, Primary Examiner. 

1. AN ILLUMINATABLE DIAL COMPRISING A CUP-SHAPED MEMBER OF LIGHT TRANSMITTING MATERIAL HAVING A DISPLAY FIELD FACE PORTION AND A PERIPHERAL FLANGE, SAID FLANGE HAVING A LAMP RECEIVING OPENING THEREIN, THE EDGE OF SAID FLANGE BEING STEPPED SO AS TO DEFINE INTERNALLY REFLECTING SURFACES INCLINED TRANSVERSELY OF THE FLANGE AND WITH RESPECT TO SAID FACE PORTION FOR DIRECTING LIGHT MOVING PERIPHERALLY OF SAID FACE PORTION FROM SAID OPENING TOWARD THE FACE PORTION OF SAID MEMBER, AND SAID DISPLAY FIELD FACE PORTION OF THE MEMBER BEING TAPERED IN THICKNESS INWARDLY FROM SAID FLANGE SO AS TO DISPERSE LIGHT FROM SAID FLANGE OVER SAID FACE. 